Histopathological factors affecting the extraction of high quality genomic DNA from tissue sections for next-generation sequencing

Validation of Modaplex POLE mutation assay in endometrial carcinoma

The TCGA-based molecular classification of endometrial cancer has emerged as an important tool to stratify patients according to prognosis. A simplified scheme has been proposed, by using immunohistochemistry for p53, MSH6, and PMS2 and a molecular test for POLE mutations (NGS or Sanger sequencing, techniques that are not available in many centers worldwide). In this study, we validate a novel method that allows simultaneous analysis of multiple pathogenic POLE mutations. The Modaplex technology integrates polymerase chain reaction and capillary electrophoresis. The design of this study encompassed 4 different steps: (1) a retrospective-pilot phase, with 80 tumors, balancing the four molecular subgroups. (2) A retrospective phase of 25 tumors obtained between 2016 and 2020, and 30 tumors obtained between 2000 and 2015. (3) An inter-laboratory corssavalidation step with 19 cases (belonging to phases 1 and 2). (4) A prospective cohort of 123 tumors, of unknown POLE status, with simultaneous validation by Sanger sequencing. A total of 258 samples were analyzed. In the first and second phases, the test showed positive/negative predictive values of 100%, by correctly identifying POLE mutation status in 79/79 and 55/55 cases. Phase 3 showed 100% of inter-laboratory consistency. Phase 4 showed 16 positive samples out of the 123 prospective cases. Overall, the test has revealed sensitivity and specificity of 100%, identifying a total of 47 POLE-mutated tumors. We have shown that this technique allows faster and easier identification of multiple pathogenic POLE mutations with high robustness and confidence when comparing to other tests such as Sanger sequencing.

Triple-negative breast cancer and basal-like subtype : Pathology and targeted therapy

Triple-negative breast cancer (TNBC) is a heterogenous disease. For personalized medicine, it is essential to identify and classify tumor subtypes to develop effective therapeutic strategies. Although gene expression profiling has identified several TNBC subtypes, classification of these tumors remains complex. Most TNBCs exhibit an aggressive phenotype, but some rare types have a favorable clinical course. In this review, we summarize the classification and characteristics related to the various TNBC subtypes, including the rare types. Therapeutic methods that are suitable for each subtype are also discussed. Of the intrinsic breast cancer subtypes identified by gene expression analysis, the basal-like subtype specifically displayed decreased expression of an estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) cluster. We also present results that characterize the TNBC and basal-like phenotypes. TNBC may be categorized into four major classes : basal-like, immune-enriched, mesenchymal, and luminal androgen receptor. Therapeutic strategies for each subtype have been proposed along with newly approved targeted therapies for TNBC, such as immune checkpoint inhibitors. Understanding the classification of TNBC based on gene expression profiling in association with clinicopathological factors will facilitate accurate pathological diagnosis and effective treatment selection. J. Med. Invest. 68 : 213-219, August, 2021.

Real-world data on microsatellite instability status in various unresectable or metastatic solid tumors

Microsatellite instability‐high (MSI‐H) is an important biomarker for predicting the effect of immune checkpoint inhibitors (ICIs) on advanced solid tumors. Microsatellite instability‐high is detected in various cancers, but its frequency varies by cancer type and stage. Therefore, precise frequency is required to plan ICI therapy. In this study, the results of MSI tests actually carried out in clinical practice were investigated. In total, 26 469 samples of various cancers were examined between December 2018 and November 2019 to determine whether programmed cell death‐1 blockade was indicated. The results of MSI tests were obtained for 26 237 (99.1%) of these samples. The male : female ratio was 51:49 and mean age was 64.3 years. In all samples, the overall frequency of MSI‐H was 3.72%. By gender, the frequency of MSI‐H was higher in female patients (4.75%) than in male patients (2.62%; P < .001). A comparison by age revealed that the frequency of MSI‐H was significantly higher in patients younger than 40 years of age (6.12%) and 80 years or older (5.77%) than in patients aged between 60 and 79 years (3.09%; P < .001). Microsatellite instability‐high was detected in 30 cancer types. Common cancer types were: endometrial cancer, 16.85%; small intestinal cancer, 8.63%; gastric cancer, 6.74%; duodenal cancer, 5.60%; and colorectal cancer, 3.78%. Microsatellite instability‐high was detected in cancer derived from a wide variety of organs. The frequency of MSI‐H varied by cancer type and onset age. These data should prove especially useful when considering ICI treatment.